U of T's John Peever is one of the experts selected for the multidisciplinary panel that examined hundreds of studies to determine how much sleep people need at every stage of life (photo by Johnny Guatto)

How much sleep do you really need? That depends: how old are you?

If you don’t remember reading about Professor John Peever’s latest research you might not be getting enough sleep. 

The University of Toronto neurobiologist was a co-author on the first peer-reviewed paper to recommended sleep times across the human lifespan. Peever represented the University of Toronto and the American Physiological Society on an international panel of experts appointed to determine how much sleep people of all ages need. 

The study received international attention. Recently the subject of David Letterman’s Top 10 list, it also picked up coverage on the Today Show, NBC News, TIME and The Daily Mail.

Peever discussed his findings and the importance of getting enough sleep with U of T News writer Michael Kennedy.  

Why was the study undertaken?
When someone goes to see their doctor there are no existing guidelines concerning recommended sleep times. This paper provides a framework for healthcare workers to recommend how much sleep healthy children, teenagers, adults and elderly people require. So the study was performed to provide a consensus view from the scientific community on how much sleep you need across your lifespan. The paper summarizes all the relevant data that we have to indicate to the public how much sleep is recommended through various stages of our lives. 

Were you surprised by how much attention the report received? 
I wasn’t surprised because people have been waiting for this for a long time. 

When you go to a doctor’s office there’s the chart on the wall that says if you are six feet tall and within a certain weight range then you’re within the normal range and you’re healthy; you and your physician have a clear guideline about what is an acceptable weight range for your height. The same thing exists for blood pressure and heart rate.

A consensus definition of how much sleep the average person needs, depending on their age, is long overdue. There’s been this magical number that floats around: eight hours. But now there’s actually a paper from a panel of people who have some understanding and knowledge of how much sleep people need at different points in their lives. 

And that’s something no one has ever before.

Were you surprised by any of the findings?
I was surprised by how difficult it was to establish a consensus concerning the range of recommended sleep – particularly for infants. This age category was challenging because there is limited literature on how much sleep infants require. In determining the right amount of sleep the panel considered several categories:  general health, cognitive health, and physical health since, for example, there’s a sparsity of information about what constitutes cognitive health in an infant. 

What are some of the health risks associated with not getting enough sleep?
The most obvious health risk of not getting enough sleep is on general cognitive performance and then getting behind for example the wheel of a car and driving sleepy. Hopefully this guideline will provide people with a clear indication that there is an appropriate range of recommended sleep and what that range is. There is a pervasive attitude today of not appreciating how much sleep we all need in order to properly function. One of the goals of the National Sleep Foundation is to inform people that sleep isn’t a dispensable part of their lifestyle.

Another point to illustrate the importance of sleep is a recent study that demonstrated how even mild sleep loss can impair an athlete’s ability to perform at their best. Now these are elite athletes, but we’re still seeing the importance of a full night’s sleep on athletic abilities. 

There are also studies showing that sleep loss may potentiate the accumulation of a nasty protein called beta-ameloid that is associated with Alzheimer’s disease. There’s an evolving concept in the field of sleep medicine that sleep loss may actually accelerate certain types of neurodegeneration. Although this data is preliminary it nonetheless underscores that sleep may function to help repair brain cell function, and that sleep loss could speed up the development of some neurodegenerative processes.

Another helpful example is the collection of studies showing that academic performance in children is impacted by sleep loss, so kids who don’t get enough sleep have poorer abilities to perform well in school.

There has been a lot of talk about the negative impact e-readers and iPads can have on sleep quality and duration. Did your study examine this phenomenon? 
For this study we didn’t look at how lifestyle impacts your sleep quality. We certainly discussed the impact electronic readers have on sleep quality but it fell outside the scope of the goal of the study – to say how much sleep you should be getting rather than here are the things that are impeding you from getting that amount of sleep. So the study didn’t specifically address such things, although it’s crystal clear that visual stimulation can negatively impact your ability to fall and stay asleep. 

Sleep requirements

  • Newborns (0-3 months): 14-17 hours each day (previously 12-18)
  • Infants (4-11 months): 12-15 hours (previously 14-15)
  • Toddlers (1-2 years): 11-14 hours (previously 12-14)
  • Preschoolers (3-5): 10-13 hours (previously 11-13)
  • School-age children (6-13): 9-11 hours (previously 10-11)
  • Teenagers (14-17): 8-10 hours (previously 8.5-9.5)
  • Younger adults (18-25): 7-9 hours (new age category)
  • Adults (26-64): Sleep range did not change and remains 7-9 hours
  • Older adults (65+): 7-8 hours (new age category)

 (Read more about Peever's work on sleep and paralysis and on acting out dreams.) 

Michael Kennedy writes about health and wellbeing for U of T News. This interview has been condensed and edited.

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